Experimental investigation on enhancement of ammonia-water falling film generation by adding ZnFe2O4 nano-particles.

This paper presents a falling film generating apparatus for testing ammonia vapor generation amount and the generation rate with or without Zinc ferrite (ZnFe2O4) nano-particles. The comparative experiments are based on influences of different concentrations of nano-particles, surfactant, ammonia-water and also hot water temperature. Experimental results show that the test bench can directly obtain the ammonia vapor amount. And by adding proper mass fraction of ZnFe2O4 with sodium dodecyl benzene sulfonate(SDBS) into ammonia water can improve the generation rate of ammonia vapor. When the concentration of ammonia-water, namely the base fluid changes among 25% to 40%, the effective generation ratio can be increased by 60% by adding ZnFe2O4 with mass fraction of 0.1% and SDBS with mass fraction of 0.05%. However, only adding the dispersant SDBS will produce certain inhibitory effect on generation amount. In order to achieve optimal results, both the dispersion stability and whether it can play a positive effect should be taken into account. Combined with the absorption enhancement effect, we know that nano-particles have great effect on both the absorption and generation process in ammonia water absorption refrigeration systems (AARS), therefore, adding optimum dispersion of nano-fluid into ammonia-water to enhance the COP of AARS should have a more promising future for their commercial application.